The Influence Mechanism of Alternating Magnetic Field on Microstructure and Mechanical Properties of Ti-6Al-4V Alloy.

This research investigated the effects of magnetic field intensity and frequency on the microstructure and mechanical characteristics of Ti-6Al-4V welding using magnetically controlled narrow gap TIG with a variety magnetic field parameters. The effects of magnetic field intensity and magnetic field frequency on the microstructure and mechanical properties of Ti-6Al-4V joint were studied. It is shown that primary α and β phases make up the base metal's (BM) microstructures in the joint. The microstructure of the fusion zone (FZ) in all welding conditions comprises of acicular α′ and acicular α with various contents and sizes. The weld width grows and the depth of fusion reduces as the magnetic field strength increases due to the Lorentz force's increased energy distribution to the side wall. When the magnetic field frequency rises, the arc's residence time on the side wall decreases, resulting in a reduction in weld breadth and an increase in fusion depth. Martensite content and size can be impacted by magnetic field intensity and frequency, and the rule was constant. This was related to the stirring effect of magnetic field on molten pool and the thermal effect of induced current. The optimum mechanical characteristics for the Ti-6Al-4V joint were attained when the magnetic field intensity and frequency was 6.5 mT and 10 Hz, respectively. At this time, the average hardness of FZ (330.8 HV) and heat affected zone (331.6 HV) were higher than that of BM (316.3 HV). The tensile strength of the joint can reach 95.79% of the BM. This work provides an instructive path for efficient welding of large-thickness titanium alloys. [ABSTRACT FROM AUTHOR]